On the 20th January 1974, test pilot Phil Oestricher unintentionally took to the skies in what was the first ever flight of an F-16. Adam Duffield looks back at the 40 year history of one of the most successful fighter jets of modern times.

In the 1960s the United States Air Force recognised that the nature of air-to-air combat was evolving and the current generation of fighters were struggling in combat against their Soviet designed counterparts and was evidenced by experiences during the Vietnam War. As a result, two programs were initiated to develop aircraft that met the future needs – the first being the F-X (Fighter-Unknown) program that led to the McDonnell Douglas F-15 and the second the Lightweight Fighter Program (LWF), later renamed the Air Combat Fighter (ACF) program, which led to the General Dynamics F-16.

The main requirements for the LWF program were based around a small, 20,000lb jet that was agile and capable of combat at speeds of up to Mach 1.6 and these were partly evaluated based upon Col. John Boyd’s theory of Energy-manoeuvrability – a method of determining an aircraft’s performance from flight characteristics such as thrust, drag, weight and size. Col. Boyd, an ex-USAF F-86 Sabre pilot, was a military strategist and analyst specialising in air-to-air combat tactics and, as well as working on the F-15 program, was one of the main driving forces behind the LWF program and believed that the end result would be the most capable air fighter available.

During 1972, design proposals were submitted by a total of five manufacturers – Boeing, General Dynamics, Lockheed, Northrop and Vought however only those from General Dynamics and Northrop were taken forward into the prototype phase resulting in the YF-16 and YF-17aircraft from the respective companies – two examples of each being built. A fly-off between the two types followed during which they were evaluated for performance and handling characteristics along with combat tests against other aircraft types. During this time there was also a change to the design requirements to allow provision not only for pure fighter but fighter-bomber capabilities which would make the resultant aircraft a much more versatile platform and less of a threat to the F-15 program.

The USAF finally selected the General Dynamics YF-16 as the winner in January 1975 leading to over 4500 examples being built since. This isn’t to say the work carried out by Northrop was wasted – whilst the YF-17 may not have won the LWF battle, realisation from the US Navy that they too required a new aircraft led to the YF-17 becoming the design basis for another highly successful jet – the McDonnell Douglas F-18.

The YF-16, and subsequently F-16 was the next step up from its predecessors and incorporated a number of new and unique features. It was designed from the very start with a fly-by-wire control system that meant control surfaces are controlled by on-board computers rather than the previously traditional mechanical systems. This also meant that the aircraft could break traditional design when it came to the center of gravity and it became the first aircraft that was unstable by design. Although this may sound dangerous, the digital fly by wire system ensured that the required control corrections to maintain stability in flight were made automatically. Whilst it had featured on a number of prototype aircraft, the F-16 was the first to use this fully digital system in production variants. Pilot visibility was also considered a key factor and the resultant canopy was design as a ‘bubble’ containing no frame or joints in front of the pilot that could impede the view. It was also designed to be capable of handling 9G and to aid in this an increased angle of seat incline to 30 degrees was included along with repositioning of the joystick from the traditional central column to the side of the cockpit in order to reduce strain on the pilot in those high G-load manoeuvres.

As with many development aircraft, the YF-16 suffered a few teething problems. The very first flight was in fact made unintentionally during a high speed taxi run. Test Pilot Phil Oestricher was in control of the aircraft (72-1567) for the test when pilot-induced oscillations occurred. These are generated as a result of continued corrections to the controls that are made in opposite directions leading to, in some instances, a complete loss of control. In this instance however it led to strikes to the tail, left wingtip and right stabiliser and, with the aircraft heading towards the edge of the runway, Oestricher opted to take off rather than risk further damage to the airframe. Following a 6 minute flight, the aircraft returned to safely to the ground allowing repairs to be carried out prior to its official test flight on 2nd February 1974. The program also suffered an issue with the Pratt & Whitney F100-PW-200 turbofan engine, a minor variant of the engine used in the F-15, that resulted in a loss of power that later discovered to be caused by a faulty fuel control valve.

It was not just the United States that were after a new fighter aircraft during this time. With the impending retirement of the Lockheed F-104 Starfighter from service, 4 NATO members were also in the market – Belgium, Denmark, Norway and the Netherlands. With a firm commitment to the type from the US, these nations also committed to the F-16 leading to the establishment of license building facilities for SABCA in Belgium and Fokker in the Netherlands. Since then, further license build facilities have also opened in Turkey and South Korea for production of their own aircraft.

Over the last 40 years, variants of the F-16 have made their way into service with no less than 26 different countries including Greece, Poland, Israel, UAE, Pakistan and Iraq however the United States remains by far the single largest operator of the type by country. Initial production variants were the F-16A single seat and F-16B two seat models and still form the highest volume variant produced. The main noticeable difference from the YF-16 was an altered nose cone to house radar equipment that was not present on the prototype however during its life numerous updates have been carried out which, rather than changing codes, are represented by block numbers.

The very first models built of the F-16A and F-16B are referred to as Block 1 with the first of the type (F-16A 78-0001) being delivered to USAF during August 1978. These Block 1 models were also received by the 4 other initial air forces that operated them. The first upgrade specification was Block 5 and it contained mostly internal upgrades with the only externally distinguishable feature being the change in color from black to grey of the radome. In 1980, Block 10 upgrades followed which, again, were all internal improvements and it wasn’t until the Block 15 updates starting in 1981 that major external updates were seen. Two additional hard points were added towards the centre front of the aircraft, mounted on either side of the air intake to enable the carrying of additional weapons and equipment. To counteract this increase in weight and balance, a larger horizontal stabiliser was also fitted to all Block 15 aircraft. Starting in 1988 the A and B models were delivered as Block 15OCU specification (Operational Capability Update) which included a power plant change to the more powerful and reliable Pratt & Whitney PW-220 engine along with structural strengthening, increased weapon capability and some cockpit features carried across from the more advanced F-16C/D models that entered production 4 years earlier. A year after the first Block 15OCU delivery, a mid-life update (MLU) study was carried out to investigate life extension options for the A/B model airframes build for the USAF and 4 European nations. Whilst the USAF did not proceed with these, the 4 European nations went ahead leading to the development of the F-16AM/BM designations. The purpose of the MLU was to improve the cockpit and avionics suite to the same standard as the F-16C/D Block 50/52 in build at the same time along with additional weapons capability and reliability improvements. One of the most noticeable external results of the upgrade is the Identification Friend or Foe (IFF) sensor that can be seen by 4 small shark fin style antennas in front of the canopy.

Whilst the F-16A/B was still being built and developed, 1984 saw the introduction of its replacement in the shape of the F-16C single seat and F-16D two seat models. Initially delivered as Block 25 and utilising the same Pratt & Whitney PW-200 engine as the A/B models, a number of improvements were brought in, some of which eventually found their way back into the A/B upgrade programs. A new Westinghouse radar system gave the C/D models an improved capability especially within the precision night attack role. For the first time the F-16 was also capable of beyond visual range engagements and a massively upgraded cockpit provided an improved HUD, multi-function displays and fire control systems. The first F-16C took to the skies in June 1984 and was delivered into the hands of USAF the following month.

During the same time USAF were looking into options around reducing the costs of engine supply and introduced the Alternative Fighter Engine (AFE) program aimed at identifying a second supplier for the aircraft. Not only was the competition between two different manufacturers designed to drive costs down it also meant that air force weren’t reliant upon a single supplier whereby, as had been experienced with the F-16A/B, an engine related issue could ground the entire fleet. The program led to the revised Pratt & Whitney PW-220 (later fitted to the F-16A/B) and the General Electric F110 engines being available for use with the common engine bay. All block upgrade numbers from this point enable fast identification of the engine types fitted – blocks ending ‘0’ are fitted with the General Electric powerplant and those ending ‘2’ the Pratt & Whitney with the first of the upgrades reflecting this being Block 30/32. With a common engine bay capable of carrying both engines with minimal changes the original intention was for this to be possible out in the field if required however it was soon found that the air intake requirements for the GE-F110 were greater than the PW-220 leading to a larger air intake being fitted to Block 30’s only. Additional improvements to the 30/32 variants included further weapon compatibility enhancements and the installation of a ‘black box’ flight recorder amongst others. The GE-110 powered Block 30 rolled out in mid-1986 was delivered in much greater quantities than the Block 32 that started being delivered in June 1987.

The next upgrade blocks followed quickly in 1988 with the Block 40/42 deliveries which were fundamentally based around the LANTIRN capability – Low Altitude Navigation and Targeting Infrared for Night. Developed by Lockheed Martin, the system is based upon a pair of pods mounted to the central chin mount points on the airframe. The first is the AN/AAQ-13 Navigation pod with the main features being a Terrain Following Radar (TFR) and Forward Looking Infrared Red (FLiR) camera. The TFR is linked to the aircraft flight controls allowing full autonomous flight down to altitude of just 100ft along with evasive terrain avoidance whilst the FLiR provides imagery on the HUD to enable improved navigation and feature recognition in poor visibility conditions. The second pod is the AN/AAQ-14 Targeting pod featuring another FLiR along with a laser designator. Working with the on-board weapons systems it allows laser designation of targets for laser guided weapons along with camera imagery that can be displayed upon the multi-function displays. This supplementary equipment required some additional strengthening around the airframe including the undercarriage which was also lengthened to allow clearance for the LANTIRN system. Again, the Block 40 outnumbered the delivery of the Block 42 and, whilst still officially F-16C/D models, they unofficially became designated the F-16CG/DG by the USAF.

The last official block designation for the F-16C/D is the 50/52 and features the higher performance General Electric F110 and Pratt & Whitney PW-229 engines respectively. Improved navigational equipment and further enhancements to weapons capability also took place and the first of the type was delivered in October 1991. The change in engine specifications also led to a swing back to the Pratt & Whitney power plants however the split between the two was much more even. Further enhancements to the Block 50/52 specification were made bringing in the 50/52+ designation. Improvements in radar systems were introduced however the most noticeable changes related to the addition of Conformal Fuel Tanks (CFT) and an enlarged spine housing additional avionics equipment for the two seat model. Whilst the USAF haven’t order any of the 50/52+ models Greece, Poland and Singapore are amongst the countries that have.

On top of the main block level modification standards many blocks also contained sub-block levels with much smaller changes and, whilst the F-16A/B and F-16C/D models represent the vast majority of all that have been built, there are many more specialised variants that exist making the F-16 possibly one of the most highly developed of the 4th generation fighter jets. Two of these are the F-16N which was developed from the F-16C/D Block 30 for use as an aggressor training aircraft with the US Navy and the F-16 Air Defence Fighter that was converted for use with the Air National Guard from F-16A/B Block 15 aircraft. In addition a number of aircraft were converted over the years for development use of new systems (and not just for the F-16) such as ground collision avoidance and low-observable asymmetric nozzle. However, two of the most advanced F-16 developments relate to the most recent variants. In use only with the UAE Air Force, the F-16E/F Block 60 includes a whole host of improvements making it the most potent version yet including inbuilt Northrop Grumman AN/ASQ-28 Internal FLiR and Targeting system that replaces the externally mounted LANTIRN system and advanced electronic warfare equipment including countermeasure and jamming systems along with further cockpit improvements and the latest weapon compatibility. Possibly at the opposite end of the scale, although still highly advanced and very much in development, is the QF-16 Aerial Target. With the option of being flown both with and without a pilot they are being developed to replace the QF-4 airframes that are currently being phased out within the USAF. These aircraft are used for live fire air-to-air combat to give realistic combat experience to pilots and there are currently 6 aircraft being converted for evaluation purposes with the first having flown, unmanned, on 19th September 2013.

Over the last 40 years the F-16 has become one of the most versatile fighter jet platforms in the world and its widespread use by foreign forces is testament to this. Whilst the focus may now be on development of 5th generation fighters, technology and design elements from the F-16 will no doubt play a part. With the latest variants only recently having been delivered to customers, unmanned versions still very much at the start of their development lifecycle and second hand sales to existing and new air forces such as Iraq, skies around the world will continue to be home to the F-16 for a long time to come.

Coming soon in part 2 we look in more detail at the forces operating the F-16, its operational history and display teams that use the aircraft.